Mechanical Behavior of Prestressed Composite Soil Nailing under Construction

Soil nailing supporting technology is widely used in the bracing of foundation pit,soil nailing and pre-stressed anchor combined is a new composite soil nailing structure for foundation pit.This paper involves two foundation pits which one of them is about 9.0 M while another one is about 16.0 M in depth.Pre-stressed composite soil nailing is used to support the stability while excavating.The deeper pit has 2 rows of shallow anchors and 8 rows of soil-nails.The another one has one row of shallow anchor and 5 rows of soil-nails.The purpose of the research in this article intends to find out how pre-stressed anchor influence on the axial force of soil-nails and failure surface.Reinforcement meter of soil-nails and stress detector of pre-stressed anchor are used to do field test on monitoring the axial force of soil nails and pre-stressed cable during the pit excavating.Two conclusions have been made from the results:First,the change of axial force caused by pre-stressed anchors to the soil nails is diverse in different positions,what is more,this change is also distinct in one soil nail of different positions.Second,the failure surface turns to be different up and below the pre-stressed anchors.This difference gets more obvious as more pre-stressed anchors are used.